Conventionally known is a technique of displaying two images shot from two viewpoints on a monitor so as to display an image that can be viewed stereoscopically by a user using a dedicated device such as stereoscopic glasses. Furthermore, in recent years, also known is a technique of displaying images (for example, nine images) shot from a plurality of viewpoints on a monitor using a light beam controller such as a lenticular lens so as to display an image that can be also viewed stereoscopically by a user with naked eyes. A plurality of images to be displayed on a monitor that can be viewed stereoscopically are generated by estimating depth information of an image shot from one viewpoint and performing image processing using the estimated information in some cases.
As medical image diagnostic devices such as X-ray computed tomography (CT) devices, magnetic resonance imaging (MRI) devices, and ultrasonography devices, devices that can generate three-dimensional medical image data (hereinafter, volume data) have been put into practice. Such a medical image diagnostic device generates a flat image for display by executing various pieces of image processing on volume data and displays the generated flat image on a general-purpose monitor. For example, the medical image diagnostic device executes volume rendering processing on volume data so as to generate a two-dimensional rendering image on which three-dimensional information for a subject has been reflected, and displays the generated rendering image on the general-purpose monitor.